Cellulose acylate film, manufacturing method of cellulose acylate film, optically compensatory sheet, polarizing plate and liquid crystal display device

Abstract

A cellulose acylate film that has a crystallization index expressed by expression (A) as defined in the specification of from 0.70 to 1.02 and a modulus of elasticity in every arbitrary direction of an in-plane of the cellulose acylate film of from 3,800 MPa to 6,000 MPa; a manufacturing method of a cellulose acylate film comprising: casting a dope on a support; drying the dope on the support, so as to form a film; peeling the film from the support; and subjecting the film to a stretching treatment, wherein a crystallization index expressed by expression (A) of the film after peeling and before stretching is from 0.70 to 1.00; an optically compensatory sheet comprising the cellulose acylate film; and a polarizing plate and a liquid crystal display device using the optically compensatory sheet.

1. A cellulose acylate film that has a crystallization index expressed by expression (A) of from 0.75 to 0.95 and a modulus of elasticity in every arbitrary direction of an in-plane of the cellulose acylate film of from 3,800 MPa to 6,000 MPa,
   Crystallization index=(X-ray diffraction intensity at 2θ of 27°)/(X-ray diffraction intensity at 2θ of 25°),  (A) 
 wherein a viscosity average polymerization degree of the cellulose acylate is from 350 to 500, and a value of Mw/Mn of the cellulose acylate is 2.0 to 3.0 in which Mw is a mass average molecular weight of the cellulose acylate and Mn is a number average molecular weight of the cellulose acylate. 
 
     
     
       2. The cellulose acylate film according to  claim 1 ,
 wherein the cellulose acylate is a cellulose acetate. 
 
     
     
       3. The cellulose acylate film according to  claim 1 , which comprises a retardation developer. 
     
     
       4. The cellulose acylate film according to  claim 3 ,
 wherein the retardation developer is a compound represented by formula ( 1 ): 
 
       
         
           
           
               
               
           
         
         wherein Ar 1 , Ar 2  and Ar 3  each independently represents an aryl group or an aromatic heterocyclic ring; 
         L 1  and L 2  each independently represents a single bond or a divalent linking group; and 
         n represents an integer of 3 or more, and a plurality of Ar 2 's and a plurality of L 2 's each may be the same or different. 
       
     
     
       5. The cellulose acylate film according to  claim 4 ,
 wherein the compound represented by formula (1) is a compound represented by formula (2): 
 
       
         
           
           
               
               
           
         
         wherein R 11 , R 12 , R 13 , R 14 , R 15 , R 16 , R 21 , R 22 l R 23  and R 24  each independently represents a hydrogen atom or a substituent; 
         Ar 2 represents an aryl group or an aromatic heterocyclic ring; 
         L 2  and L 3  each independently represents a single bond or a divalent linking group; and 
         n represents an integer of 3 or more, and each of a plurality of Ar 2 's and a plurality of L 2 's may be the same or different. 
       
     
     
       6. The cellulose acylate film according to  claim 3 ,
 wherein the retardation developer is at least one compound selected from compounds represented by any of formulae (I), (II), (III) and (IV): 
 
       
         
           
           
               
               
           
         
         wherein R 1  represents an aromatic ring having a substituent on at least one of ortho- and meta-positions, or a heterocyclic ring; 
         R 2  represents an aromatic ring having a substituent, or a heterocyclic ring, provided that when R 1  represents an aromatic ring having a substituent on at least one of ortho- and meta-positions and R 2  represents an aromatic ring having a substituent, R 1  and R 2  are not the same; 
         X 1  represents a single bond or —NR 3 —; 
         X 2  represents a single bond or —NR 4 —; 
         X 3  represents a single bond or —NR 5 —; and 
         R 3 , R 4  and R 5  each independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, alkenyl group, aryl group or heterocyclic group; 
       
       
         
           
           
               
               
           
         
         wherein R 6  represents an aromatic ring having a substituent on para-position, or a heterocyclic ring; 
         R 7  represents an aromatic ring having a substituent, or a heterocyclic ring, provided that when R 6  represents an aromatic ring having a substituent on para-position and R 7  represents an aromatic ring having a substituent, R 6  and R 7  are not the same; 
         X 4  represents a single bond or —NR 13 —; 
         X 5  represents a single bond or —NR 14 —; 
         X 6  represents a single bond or —NR 15 —; and 
         R 13 , R 14  and R 15  each independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, alkenyl group, aryl group or heterocyclic group; 
       
       
         
           
           
               
               
           
         
         wherein R 8  represents an aromatic ring having a substituent on at least one of ortho- and meta-positions, or a heterocyclic ring; 
         X 7  represents a single bond or —NR 23 —; 
         X 8  represents a single bond or —NR 24 —; 
         X 9  represents a single bond or —NR 25 —; and 
         R 23 , R 24  and R 25  each independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, alkenyl group, aryl group or heterocyclic group; 
       
       
         
           
           
               
               
           
         
         wherein R 9 , R 10  and R 11  each independently represents a different aromatic ring or heterocyclic ring; 
         X 10  represents a single bond or —NR 33 —; 
         X 11  represents a single bond or —NR 34 —; 
         X 12  represents a single bond or —NR 35 —; and 
         R 33 , R 34  and R 35  each independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, alkenyl group, aryl group or heterocyclic group. 
       
     
     
       7. The cellulose acylate film according to  claim 1 ,
 wherein the cellulose acylate film has an in-plane retardation value (Re) of from 20 to 200 nm and a retardation value in a thickness direction (Rth) of from 70 to 400 nm. 
 
     
     
       8. The cellulose acylate film according to  claim 1 ,
 wherein a difference between a maximum value and a minimum value of an orientation angle in an arbitrary 60 mm×60 mm square in the cellulose acylate film is from 0° to 0.40°. 
 
     
     
       9. An optically compensatory sheet comprising a cellulose acylate film according to  claim 1 . 
     
     
       10. The optically compensatory sheet according to  claim 9 , which further comprises an optically anisotropic layer directly or indirectly on the cellulose acylate film. 
     
     
       11. A polarizing plate comprising:
 a polarizing film; and 
 at least two transparent protective films, wherein at least one transparent protective film is disposed on each side of the polarizing film, 
 wherein at least one of the at least two transparent protective films is an optically compensatory sheet according to  claim 9 . 
 
     
     
       12. A liquid crystal display device comprising:
 a liquid crystal cell; and 
 at least two polarizing plates, wherein at least one polarizing plate is disposed on each side of the liquid crystal cell, 
 wherein at least one of the at least two polarizing plates is a polarizing plate according to  claim 11 . 
 
     
     
       13. The liquid crystal display device according to  claim 12 ,
 wherein a display mode of the liquid crystal display device is a VA mode. 
 
     
     
       14. A manufacturing method of a cellulose acylate film comprising:
 casting a dope on a support; 
 drying the dope on the support, so as to form a film; 
 peeling the film from the support; and 
 subjecting the film to a stretching treatment, 
 wherein a crystallization index expressed by expression (A) of the film after peeling and before stretching is from 0.75 to 0.95,
   Crystallization index=(X-ray diffraction intensity at 2θ of 27°)/(X-ray diffraction intensity at 2θ of 25°)  (A) 
 
 
       wherein a modulus of elasticity in every arbitrary direction of an in-plane of the cellulose acylate film is from 3,800 MPa to 6,000 MPa, wherein a viscosity average polymerization degree of the cellulose acylate is from 350 to 500, and a value of Mw/Mn of the cellulose acylate is 2.0 to 3.0, in which Mw is a mass average molecular weight of the cellulose acylate and Mn is a number average molecular weight of the cellulose acylate. 
     
     
       15. The manufacturing method of a cellulose acylate film according to  claim 14 ,
 wherein a content of a residual solvent in the film at a time of beginning of the stretching treatment expressed by following expression is from 1 to 40 mass %,
   Residual solvent content=(mass of residual solvent)/(mass of solids content). 
 
 
     
     
       16. A cellulose acylate film obtained by the manufacturing method according to  claim 14 .